Lecture on Gas Laws in Electrical Chemistry

Introduction

• Focus on important formulas and equations related to gas laws in electrical chemistry.
• Fast-paced delivery with a lot of information.

Pressure

• Definition: Pressure = Force / Area
• Units:
  • Physics: 1 Pascal (Pa) = 1 Newton/m²
  • Chemistry: 1 atm = 101,300 Pascals = 101.3 kPa = 760 mmHg = 14.7 psi

Ideal Gas Law

• Equation: PV = nRT
  • P = Pressure (atm)
  • V = Volume (liters)
  • n = Moles
  • R = Gas constant (0.08206 L·atm/mol·K or 8.3145 J/mol·K)
  • T = Temperature (Kelvin)
• Temperature Conversion:
  • Kelvin = Celsius + 273.15
• Use of R:
  • Chemistry: R = 0.08206 L·atm/mol·K
  • Physics: R = 8.3145 J/mol·K

Combined Gas Law

• Equation: P1V1/T1 = P2V2/T2
  • Pressure and volume units must match; temperature in Kelvin.

Boyle's Law

• Equation: P1V1 = P2V2
  • Relationship: Inverse between pressure and volume.

Charles's Law

• Equation: V1/T1 = V2/T2
  • Relationship: Direct between volume and temperature.

Gay-Lussac's Law

• Equation: P1/T1 = P2/T2
  • Relationship: Direct between pressure and temperature.

Avogadro's Law

• Equation: V1/N1 = V2/N2
  • Relationship: Direct between volume and moles of gas.

Molar Mass and Density

• Equation: PV = (m/MW)RT
  • Density: Density = PM/RT
  • Use these equations to calculate molar mass and density.

Standard Temperature and Pressure (STP)

• Conditions: 273 K (0°C) and 1 atm.
• Conversions: 1 mol gas = 22.4 L at STP.

Dalton's Law of Partial Pressures

• Total Pressure: Sum of partial pressures of individual gases.
• Formula: Partial pressure = Mole fraction × Total pressure.
• Mole fraction = Moles of gas / Total moles

Kinetic Energy of Gases

• Relationship: Directly proportional to temperature.
• Use R = 8.3145 J/mol·K for calculations.

Root Mean Square Velocity

• Equation: sqrt(3RT/MW)
  • MW must be in kg/mol for calculations.

Graham's Law of Effusion

• Concept: Rate of effusion ∝ 1/sqrt(MW)
• Equation: R2/R1 = sqrt(MW1/MW2)
  • Heavy gases effuse slower; lighter gases effuse faster.
• Time vs. Rate Relationship: Time ∝ 1/Rate